fix: close session before doing long latency operation (#22306)

api/core/rag/datasource/retrieval_service.py

@@ -3,7 +3,7 @@ from concurrent.futures import ThreadPoolExecutor
 from typing import Optional
 
 from flask import Flask, current_app
-from sqlalchemy.orm import load_only
+from sqlalchemy.orm import Session, load_only
 
 from configs import dify_config
 from core.rag.data_post_processor.data_post_processor import DataPostProcessor
@@ -144,7 +144,8 @@ class RetrievalService:
 
     @classmethod
     def _get_dataset(cls, dataset_id: str) -> Optional[Dataset]:
-        return db.session.query(Dataset).filter(Dataset.id == dataset_id).first()
+        with Session(db.engine) as session:
+            return session.query(Dataset).filter(Dataset.id == dataset_id).first()
 
     @classmethod
     def keyword_search(

api/core/rag/retrieval/dataset_retrieval.py

@@ -9,6 +9,7 @@ from typing import Any, Optional, Union, cast
 from flask import Flask, current_app
 from sqlalchemy import Float, and_, or_, text
 from sqlalchemy import cast as sqlalchemy_cast
+from sqlalchemy.orm import Session
 
 from core.app.app_config.entities import (
     DatasetEntity,
@@ -598,7 +599,8 @@ class DatasetRetrieval:
         metadata_condition: Optional[MetadataCondition] = None,
     ):
         with flask_app.app_context():
-            dataset = db.session.query(Dataset).filter(Dataset.id == dataset_id).first()
+            with Session(db.engine) as session:
+                dataset = session.query(Dataset).filter(Dataset.id == dataset_id).first()
 
             if not dataset:
                 return []

api/core/workflow/nodes/knowledge_retrieval/knowledge_retrieval_node.py

@@ -144,6 +144,8 @@ class KnowledgeRetrievalNode(LLMNode):
                 error=str(e),
                 error_type=type(e).__name__,
             )
+        finally:
+            db.session.close()
 
     def _fetch_dataset_retriever(self, node_data: KnowledgeRetrievalNodeData, query: str) -> list[dict[str, Any]]:
         available_datasets = []
@@ -171,6 +173,9 @@ class KnowledgeRetrievalNode(LLMNode):
             .all()
         )
 
+        # avoid blocking at retrieval
+        db.session.close()
+
         for dataset in results:
             # pass if dataset is not available
             if not dataset: